The objective of this project is to improve the diagnosis and treatment of fetal disease. Focus is placed on the prenatal diagnosis of congenital anomalies with non-invasive methods (i.e., high resolution ultrasound and Doppler color flow mapping). The most significant contribution of the laboratory was the performance of the first successful endoscopic surgical procedure in the human fetus. Transabdominal thin-gauge fetoscopy was used to identify and ligate the umbilical cord of an acardiac twin. This procedure represents a new approach to the treatment of fetal disease. We anticipate that operative fetoscopy will have a role in the treatment of other conditions such as monochorionic twins discordant for congenital anomalies, twin to twin transfusion syndrome, pedunculated fetal tumors and other fetal and placental conditions amenable to surgical treatment. The laboratory used diagnostic ultrasound to establish prenatal diagnosis of conditions heretofore undiagnosed (i.e., velamentous insertion of the umbilical cord). Intensive studies of the fetal hemodynamic system in patients with preterm labor and intrauterine growth retardation progressed. The goal of these studies is to develop non-invasive methods to assess cardiac function in the critically ill human fetus.